1 . His actions and words could lead to him________ (lose) his job(所给词的适当形式填空)

2 . It was a time when people were divided geographically, _____________ (lead) to many varieties of dialects and characters. (所给词的适当形式填空)

3 . This kind of discussion will certainly lead__________ greater differences between the two parties. （用适当的词填空）

4 . Experts warn that medical waste from hospitals, if not handled properly, may lead ________ the spread of diseases. (用适当的词填空)